feat: add custom nelc dependencies

[andrey-canon]

Description

This set the edunext packages and add the openedx-brand styles to the main scss file. Migration pr of #5

Issue # 1291

How to test?

1. run npm install
2. Open discussion -> the mfe must load with default color
3. Add the following setting and check discussion page -> the mfe must load with red color

  "CUSTOM_PRIMARY_COLORS": {
    "pgn-color-primary-base": "#AA0000"
  },

4. Add the following setting and check discussion page -> the mfe must load with green color

  "PARAGON_THEME_URLS": {
    "core": {
        "url": "https://cdn.jsdelivr.net/combine/npm/@edx/paragon@22.0.0-alpha.13/styles/css/themes/light/utility-classes.min.css,npm/@edx/paragon@22.0.0-alpha.13/dist/core.min.css"
    },
    "defaults": {
        "light": "light"
    },
    "variants": {
        "light": {
            "url": "https://css-varsify.s3.amazonaws.com/public/a9959998-0bab-4447-ada5-6819866195f3.css"
        }
    }
  },

5. check the typography

Expected result

[johanseto]

LGTM working in my local env

Screencast.from.20-10-25.09.52.44.webm